1. Technical Field
The present invention relates to microstrip antenna technology and more particularly to a microstrip antenna which utilizes electromagnetic coupling to establish signal feeding and does not need to make a through hole on the insulating substrate during its fabrication, thereby reducing the microstrip antenna processing steps and material consumption and lowering the microstrip antenna manufacturing cost.
2. Description of the Prior Art
Microstrip antennas have a low profile, can be mass-produced, and can easily be integrated into active components or circuit boards. Due to the aforesaid benefits, microstrip antennas are intensively used in various wireless communication devices, such as PGS (Global Positioning System) devices or RFID (Radio Frequency Identification) devices.
Referring to FIG. 1A and FIG. 1B, a schematic top view and bottom view of a microstrip antenna according to the prior art are shown. As illustrated, this prior art microstrip antenna 10 comprises an insulating substrate 11, a first conducting layer 13, a second conducting layer 15, a feed-in zone 171, and a conducting element 173, wherein the first conducting layer 13 is located at the top surface of the insulating substrate 11, and the second conducting layer 15 is located at the bottom surface of the insulating substrate 11. The conducting element 173 penetrates through the insulating substrate 11, the first conducting layer 13 and the second conducting layer 15, and is electrically connected to the first conducting layer 13.
The first conducting layer 13 at the top surface of the insulating substrate 11 works as the radiator of the microstrip antenna 10. The second conducting layer 15 at the bottom side of the insulating substrate 11 is a ground plane. During the operation of the microstrip antenna 10, the wireless signal is received by first conducting layer 13 and passed to RF circuit through the feed-in zone 171 and the conducting element 173. At transmitting, the RF circuit sends the wireless signal through the conducting element 173 and the feed-in zone 171 to the first conducting layer 13, enabling the first conducting layer 13 to transmit the signal wirelessly into the air.
During the preparation of the microstrip antenna 10, it needs to make a through hole through the insulating substrate 11, the first conducting layer 13 and the second conducting layer 15, and then insert the conducting element 173 through the through hole to connect the conducting element 173 to the first conducting layer 13 by forming the feed-in zone 171 in the junction between the conducting element 173 and the first conducting layer 13. However, making a through hole through the insulating substrate 11, the first conducting layer 13 and the second conducting layer 15 complicates the manufacturing process of the microstrip antenna 10 and increases the manufacturing cost of the microstrip antenna 10.